Interference avoidance in a WCDMA system

• US 8,725,157 B2
• Filed: 05/31/2007
• Issued: 05/13/2014
• Est. Priority Date: 05/31/2007
• Status: Active Grant

• Current Assignee: Telefonaktiebolaget LM Ericsson
• Original Assignee: Telefonaktiebolaget LM Ericsson
• Inventors: Ghasemzadeh, Farshid, Aqvist, Hans
• Primary Examiner(s): Hua, Quan M
• Application Number:
  US12/602,453
• Publication Number:
  US 20100178921A1
• Time in Patent Office: 2,539 Days
• Field of Search: 455/435.1, 455/63.1, 455/434, 455/435.2, 455436-444, 455/450, 455/524, 455/525, 455/552.1, 455/418, 455/422.1, 455/432.1, 455/446, 455/453, 370/310, 370/320, 370/322, 370/324, 370/341, 370/342, 370/232, 370/237, 370/241, 370328-338, 379 101- 35
• US Class Current: 455/443
• CPC Class Codes: H04W 36/04 Reselecting a cell layer in multi-layered cells
• CPC Class Codes: H04W 84/045 using private Base Stations, e.g. femto Base Stations, home Node B

Abstract

A method for a cellular system comprising base stations of a first and a second kind, which control cells of a first and second kinds, and a control function for the base station of the first kind. The control function maintains a list of cells in the vicinity of the first cell, a Neighbor Cell list, and a UE in the first cell measures transmissions from Neighbor Cells and reports them, and said UE makes Detected Set, DS, measurements, and reports them to the control function. The control function searches DS measurement reports for cells of the second kind, and if a cell of the second kind is found, a hand over of the UE is initiated, to prevent transmissions from the UE to cause interference in the base station of the second kind.

Claims

1. For use in a wireless cellular telephony system including a first base station operable in a macro cell and a second base station operable in a femto cell, said macro cell being different than said femto cell and having respective coverages that at least partially coincide, a method of operating a base station controlling node of said wireless cellular telephony system, the method comprising:

maintaining a neighbour cell list of neighbour cells in a vicinity of said first base station and a reserved list of scramble codes reserved for one or more femto base stations;

receiving a measurement report from a mobile user equipment currently associated with the first base station for transmissions between said mobile user equipment and said neighbor cells;

receiving further a detected set measurement report from said mobile user equipment for transmissions between said mobile user equipment and cells that are not indicated in said neighbour list;

upon receiving the detected set measurement report, identifying said femto cell by comparing the scramble codes in said detected set measurement report against the reserved list; and

in response to only determining that the detected set measurement report has at least one scramble code that matches the reserved list, initiating a hand over of said mobile user equipment to another operating frequency or a wireless cellular telephony system of another standard operated by said first base station to prevent transmissions from said mobile user equipment to cause interference with said second base station identified in said detected set measurement report.

2. The method of claim 1 further comprising ordering said user equipment to provide said measurement report and said detected set measurement report.

3. The method of claim 1 wherein said controlling node is a radio network controller in a WCDMA wireless cellular telephony system.

4. For use in a wireless cellular telephony system including a first base station operable in a macro cell and a second base station operable in a femto cell, said macro cell being different than said femto cell and having respective coverages that at least partially coincide, a controlling node of said wireless cellular telephony system, the controlling node comprising:

a processor; and

memory including computer program code, said memory and said computer program code configured to, with said processor, cause said controlling node to perform at least the following;

maintain a neighbour cell list of neighbour cells in a vicinity of said first base station and a reserved list of scramble codes reserved for one or more femto base stations;

receive a measurement report from a mobile user equipment currently associated with the first base station for transmissions between said mobile user equipment and said neighbor cells;

receive further a detected set measurement report from said mobile user equipment for transmissions between said mobile user equipment and cells that are not indicated in said neighbor list;

upon receiving the detected set measurement report, identify said femto cell by comparing the scramble codes in said detected set measurement report against the reserved list; and

in response to only determining that the detected set measurement report has at least one scramble code that matches the reserved list, initiate a hand over of said mobile user equipment to another operating frequency or a wireless cellular telephony system of another standard operated by said first base station to prevent transmissions from said mobile user equipment to cause interference with said second base station identified in said detected set measurement report.

5. The controlling node of claim 4 wherein said memory and said computer program code are further configured to, with said processor, cause said controlling node to order said user equipment to provide said measurement report and said detected set measurement report.

6. The controlling node of claim 4 wherein said controlling node is a radio network controller in a WCDMA wireless cellular telephony system.

7. A wireless cellular telephony system, comprising:

a first base station operable in a macro cell;

a second base station operable in a femto cell, said first cell being different than said femto cell and having respective coverages that at least partially coincide; and

a controlling node of said wireless cellular telephony system configured to;

maintain a neighbour cell list of neighbour cells in a vicinity of said first base station and a reserved list of scramble codes reserved for one or more femto base stations;

receive a measurement report from a mobile user equipment currently associated with the first base station for transmissions between said mobile user equipment and said neighbor cells;

receive further a detected set measurement report from said mobile user equipment for transmissions between said mobile user equipment and cells that are not indicated in said neighbor list;

upon receiving the detected set measurement report, identify said femto by comparing the scramble codes in said detected set measurement report against the reserved list; and

in response to only determining that the detected set measurement report has at least one scramble code that matches the reserved list, initiate a hand over of said mobile user equipment to another operating frequency or a wireless cellular telephony system of another standard operated by said first base station to prevent transmissions from said mobile user equipment to cause interference with said second base station identified in said detected set measurement report.

8. The wireless cellular telephony system of claim 7 wherein said controlling node is further configured to order said user equipment to provide said measurement report and said detected set measurement report.